What RAM To Get For E6750 OC?

[[ red-eye ]]

Hi all,

Need some advise please... I'm going to be building a E6750 rig in the next few weeks with an Asus P5K Deluxe.

I am planning on over-clocking the CPU (ofcourse ). My questions is, what RAM would be best for this... 6400, 8500...?

Thanx

 

[BillParrish]

PC6400 is probally fine for any C2D quad or otherwise based on the following.

Using a CPU mulitplier of 8 (all c2d have this multi except the E6300 and one other I cant think of, the cheapies, check your CPU)

Using an FSB setting of 400MHz (all good enthusiasts OCing boards should be able to do that)

Setting the memory mulitplier to a 1:1 ratio (the memory runs at twice the speed of the FSB, which is the way Intel designed the chipset, other ratios are available but in general you want to run at 1:1)

if you do the above your CPU is running at a very respectable OC of 8x400 = 3.2GHz and your memory is running 2 x 400 = 800 MHZ right on spec and not overclocked at all. This leaves you room to increase the FSB some more. Most decent PC6400 OCing memory will get to at least 430MHz FSB (860MHz memory speed) before you need to loosen the timings to go higher, see my sig. So typically you should be able to get somewhere near 430x8 = 3.44GHz. Of course top notch cooling and proper setup etc etc.


Some C2Ds have multi of 9 which allows a lower FSB to reach the same CPU frequencies. The lower FSB puts less stress on the board and is easier to achieve but you end up under clocking your ram. For example, 9 x 357FSB = 3.2GHz CPU speed but your memory is only running at 2x357 = 714MHz which is under its rated speed and you loose memory bandwidth. If next available memory mulitplier/divider (check each proposed board for the exact memory dividers it supports,) was 2.5 and you enabled it your CPU would still be at 3.2GHz but your memory would run at 2.5 x 357 = 892MHz which might be high on fast timings and require you to loosen timings up just to boot. In this case ram rated higher than PC6400 would be preferred.

So it just depends on how hard you are going to push it, good very respectable OC without stressing stuff pc6400 will do very well. You want to push as hard as you can get something rated a bit higher. 4GB (4x1GB typically reduces the ability to overclock just a tad)

Thats the facts. Download the manual for the board you are considering and do the easy math based on available memory dividers and see what you can do (in theory).

Also with DDR2, the price difference may not (now) be all that much and having ram rated at fast speeds never hurts.

Note that per above even basic value ram can get you to 3.2GHz if your board can do 400MHz FSB.

 

[[ red-eye ]]

Hi, thanks for your reply.

What you said makes a lot of sense

The E6750 has a multi of 8. I want to push the chip as much as I can while keeping stability (of course).

I 'thought' that by getting RAM such as PC8500, it would be more beneficial to OCing as I would be able to push up the FSB more than with PC6400 without fiddling about with RAM timings. i.e. The PC8500 wouldn't hold me back as much as PC6400. Does that make sense?

Do you think this PC6400 RAM will be good for OCing?

 

[gwai lo]

Yeah, but a lot of people don't get that far. 533x8 = 4264 MHz. If you got the cash and want to go for it, then you can...but for most people it's not needed.

Anyway, those sticks look fine, they're DDR2-800 and the timings can be loosened when you hit a wall..so it gives you some room.